Question

Given 3 is one of the roots of the quadratic equation x^2-7x+k=0.Find the value of k.

Answer 1

@UnkleRhaukus

Answer 2

roots means the value that make the equation =0

Answer 3

so since you have one root just put it instead of x the solve for k

Answer 4

(3)^2-7(3)+k=0

Answer 5

got it. answer will be k=12

Answer 6

since 3 is a root then when x = 3 y = 0

Answer 7

yes

Answer 8

thnx @AJ01 @UnkleRhaukus @triciaal

Answer 9

as shown by @AJ01

Answer 10

9?

Answer 11

i think you made a switch
the constant is ac
the sum is b

Answer 12

ax^2+bx+c =0

the sum of the roots is -b/a
the product of the roots is c/a

x^2-7x+k=0
if the roots are 3 and m

3 + m = -(-7)/1 = 7
m = 4

the product of the roots is
3 * 4 = k / 1

Answer 13

tq @UnkleRhaukus